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What is Windows Defender and how do I use it?

On this page:

About Windows Defender

Windows Defender is an antispyware program for Windows that provides real-time protection and postinfection scanning and removal. Windows Defender succeeds Windows Antispyware, and is one of several competing packages from various vendors that protect against spyware and adware (generally lumped together and called "malware").

Windows Defender is part of Windows Vista, and is available free of charge for currently licensed copies of Windows XP.

This program is unique because to develop its software definitions, it uses a "voting network", which Microsoft describes as:

"... a worldwide network of users who help discover and report new threats. Microsoft analysts review these reports and develop new software definitions to guard against the new threats, so that everyone is better protected."

Installing Windows Defender

To install Windows Defender:

  1. Download Windows Defender. You can obtain it from either IUware or Microsoft:

    Follow the on-screen instructions to validate your copy of Windows and begin downloading.

  2. Once the download is complete, run the install file.

  3. On the Welcome screen, click Next, and then Validate.

  4. At the next screen that appears, read and accept the license agreement, and then click Next.

  5. At the Help Protect Windows screen, read the descriptions, and then choose the option you want. If you are unsure which option to choose, choose the recommended settings. Click Next.

  6. Choose Complete install, and then click Next.

  7. Click Install.

  8. After installation is complete, you can choose to update and run a quick scan, or wait until later. Click Finish.

Scanning with Windows Defender

You have three options for scanning your computer with Windows Defender:

  1. Quick Scan: Runs a quick scan of the most common vulnerable areas of your computer. To run a quick scan, from the menu, either click the Scan icon, or click the arrow next to it, and then select Quick Scan.

  2. Full Scan: Scans all areas of your computer thoroughly. Running a full scan takes significantly longer than running a quick scan. To run a full scan, click the arrow next to the Scan icon, and then select Full Scan.

  3. Custom Scan: Scans only selected drives and folders. To run a custom scan:

    1. Click the arrow next to the Scan icon, and then select Custom Scan.
    2. Click the Select... button next to Scan selected drives and folders.
    3. Check the drives and folders you wish to scan, and then click OK.
    4. Click Scan Now.

Note: To cancel a scan at any time, click the Stop Scan button next to the Progress Meter.

Scheduling scans

Windows Defender gives you the flexibility to schedule automatic scans for spyware at daily or weekly intervals. By default, it will run a quick scan every morning at 2am. To adjust the automatic scanning options:

  1. Click the Tools icon.

  2. Under "Settings", click Options.

  3. Under "Automatic Scanning", check the option for Automatically scan my computer (recommended).

  4. Select a frequency, time, and type of scan.

  5. Ensure that Check for updated definitions before scanning and Apply default actions to items detected during a scan are checked.

  6. Under "Default actions", select the actions you want Windows Defender to take when detecting threats of certain alert levels. If you are unsure, use the default action.

  7. Click Save.

Using real-time protection

Real-time protection in Windows Defender is enabled by default. This ensures your computer is constantly monitored against spyware and other threats as you browse the web. To modify real-time protection options in Windows Defender:

  1. Click the Tools icon.

  2. Select Options.

  3. Scroll down to Real-time protection options.

  4. Either enable or disable real-time protection with the Use real-time protection (recommended) option.

  5. If you enable real-time protection, you can modify which individual security agents you want to run. If you are unsure about which security agents to select, use the default settings. To learn more about these security agents, click Understanding real-time protection.

  6. Click Save.